GBuffer WorldNormal Used to reconstruct Materials - Normal Map displaying incorrectly

[CupMcCakers]

After solving my issues, I now present my atlas generator!

Here is it is in action: [video]https://i.gyazo.com/003a7501ed08573af4e55de78e54090c.mp4[/video]

Hi, I’m trying to create an atlas-generator inside of UE4, and it’s going okay - but I’ve encountered a problem which i’m hoping is just due to a simple but fundamental gap in my knowledge of how normal maps work inside Unreal. I’ve had a look for people encountering the same issue but haven’t had any luck.

Here’s a video of the generator “kind of” working: [video]https://i.gyazo.com/0cb4b55e9c58b296c62849b47bc13711.mp4[/video]

So, I draw a render capture of the world normal buffer, which results in this, which looks ok:

https://i.gyazo.com/6974ed4718ee6e663b8070acdb7b6ada.jpg

However, I noticed that the compression is set to:

https://i.gyazo.com/c43c3ca28b4aeb274724c3d8d854b586.png

This is fine, as I don’t intend to use the render capture directly anyway… So I right click my capture, and turn it into a static texture, and on this one, I set it to use normal map compression:

https://i.gyazo.com/8d90d55819a7c0a88fcf93e48e1cbcac.png

However, as you probably noticed, the normal map already looks a lot darker… Which I find strange. But anyway, things get even weirder in the material editor. Where my normal map now looks like this:

https://i.gyazo.com/e52164430f603022ed99911b207140b3.png

I find that If I use a constant bias scale node with the default values, it ends up looking a lot more like it should.

https://i.gyazo.com/e0cd1e2c1ed8eb5a1318219d80360df5.png

This is actually useable, however, it is far from perfect, as all of the values in the (-1,0) range are excluded, which means the map does not display as it should. Also, I am no longer able to Flip the green channel, as the values to flip do not exist. It seems that world normals from the gbuffer sometimes need to be flipped in order to display correctly. So this is another significant problem.

If I clamp the values to the 0,-1 range and then invert the map after the bias node, you can see nothing is displayed

https://i.gyazo.com/eee83114d613cc758e2d3b8fa98ca9fc.png

This is what it looks like without the bias node:

https://i.gyazo.com/e84e19b06188c51abcde32bd2cdfbd33.png

And this is what it should look like

https://i.gyazo.com/7e2038ad0d30384977f402626108e811.png

If anybody has encountered problems like this before, or could point me to some helpful resources, that would be amazing.

[CupMcCakers]

I found and fixed the issue!

The “GBuffer” PP material which reads the scene texture can only output an Emissive Texture!

My solution was to compress the normal map into the 0-1 range

And then Uncompress it again for use in the material

A little bit of rewiring the channels later:

and we have a perfect match!

(See if you can tell which set of tiles are the source and which set of tiles are the atlas)

I hope somebody finds this useful!